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The chemical plant is characterized by a lot of equipment, pipelines and instruments connected to each other to complete the normal operation. Due to the large scale, strong production continuity, low self-control level, and many flammable, explosive and dangerous materials in the current petrochemical equipment, the height of the equipment is different, so it is not possible to adopt a fully enclosed method to solve the problem in winter in severe cold areas. Antifreeze and anticondensation problems, so the work of antifreeze and anticondensation in winter is very important. There are generally two measures for instrument antifreeze and heat preservation: one is steam heat tracing and heat preservation, and the other is electric heat tracing and heat preservation.

In the past, my country's oil refining and chemical enterprises often used steam heat tracing systems. Part of the heat released by the steam tracing heat pipe supplements the heat loss of the medium in the main pipe, and the other part is lost to the surrounding environment through the outer insulation layer of the pipe. The use of hard insulation prefabricated shells requires a space between the main pipe and the heat tracing pipe, so that the heat released by the heat tracing small pipe can almost completely compensate the heat loss of the main pipe, so the heat source consumption of this form of heat tracing is more economical. Steam tracing is generally used for heat tracing where the operating temperature of the medium in the pipe is less than 150°C.

However, due to the disadvantages of low degree of automation control, low heat conversion rate, large and complex supporting equipment, high maintenance costs, and low efficiency, steam heat tracing has been completely replaced by electric heat tracing.

As an effective pipe insulation and antifreeze solution, electric heat tracing has been widely used. Its working principle is to dissipate a certain amount of heat through the heating medium, and supplement the loss of the heated pipe through direct or indirect heat exchange, so as to meet the normal working requirements of temperature rise, heat preservation or antifreeze. Electric heat tracing has small heating temperature gradient, high power, stable and long-term action time, and can realize digital, remote, automatic control, easy equipment installation, long service life, no pollutant emission and many other advantages that steam tracing cannot achieve.

A complete instrument electric heating system usually consists of six parts: power connector, electric heating cable, electric heating end junction box, three-way junction box, two-way junction box, insulation layer, moisture-proof layer and strapping. These 6 parts support the same, one link and one link, any problem in any link will lead to failure of the instrument electric heating system.

Electric heating cables for instruments are usually divided into two types: one is constant power heating cables, and the other is self-controlling heating cables. Constant power electric heating cable has significant advantages such as high thermal efficiency, constant output, long service life, and long life. Using low-voltage power supply can realize small equipment footprint and precise control; self-controlling point heating cable output The temperature changes with the change of the ambient temperature. As the depth of the outside increases, its output power will decrease, and vice versa, it will increase. This point heating cable is suitable for areas where the ambient temperature difference changes and changes greatly. Compared with the constant power electric heating belt, the self-controlled heating belt has the advantages of energy saving, but it has the advantages of uniform heating, simple construction, low travel cost, and free cutting.

Refining and chemical enterprises adopt instrument electric heat tracing automatic temperature control system, although the one-time investment in the early stage is high, but the operating cost is low and the production efficiency is high, which can significantly improve the economic effect of the enterprise. Instrument electric heat tracing can be used in special environments, with explosion-proof function, all-weather temperature operation and long working life, with an average of more than 8 years, and there will be no liquid leakage and environmental pollution.